Our Planet's Killer Electrons Shoot Toward Space, Not Earth

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As the sun heads toward its 2013 maximum, the corresponding
increase in space weather may temporarily strip the radiation
belts around Earth of their charged electrons. But a new study of
data recorded by 11 independent spacecraft reveals that the
deadly particles are blown into space rather than cast into our
planet's atmosphere, as some scientists have suggested.

Streams of highly charged electrons zip through the Van
Allen radiation belts circling Earth. When particles from the
sun collide with the planet's magnetic field, which shields Earth
from the worst effects, the resulting
geomagnetic storms can decrease the number of dangerous
electrons.

Where those particles go is something physicists have long
puzzled over — and since they could wreak havoc on sensitive
telecommunication satellites and pose a risk to astronauts in
space, it's an important question, researchers say.

At the heart of the geomagnetic storm mystery are strange dips,
known as dropouts, in the number of charged particles in the
radiation belts. These lapses can happen multiple times per
year, but when the sun is going through an active period — as it
is now — the number can increase to several times per month,
scientists involved in the new study explained. [ Amazing
auroras from geomagnetic storms ]

Astronomers have previously suggested that the missing particles
could have been ejected toward Earth, where they might have been
absorbed by the atmosphere. This activity still could explain
some of the loss, particularly that which occurs when no
geomagnetic storm has been detected, but not all of it.

A team of scientists from the University of California, Los
Angeles, observed a geomagnetic storm in January 2011 with a
plethora of instruments. They noticed that as intense solar
activity pushes against the outer edge of
Earth's magnetic field on the daylight side, the lines can
cross, allowing the damaging electrons to escape into space.

"Those particles are entirely lost," lead scientist Drew Turner
told SPACE.com. The research is detailed in the Jan. 29
edition of the journal Nature Physics.

Although material ejected from the sun can deplete the Earth's
outer radiation belt, it can also resupply the belt with more
charged particles in only a few days, Turner said.

Previous studies have found that the volume of electrons can
spike after a solar event. When the belts are first almost
depleted, Turner's observations imply a larger influx than
previously accounted for.

The team used 11 different satellites, including NASA's five
Themis spacecraft and two weather satellites operated by the
National Oceanic and Atmospheric Administration and the European
Organization for the Exploitation of Meteorological Satellites,
to study a small geomagnetic storm. The abundance of spacecraft
allowed them to capture a complete picture of the interactions
between Earth's magnetic field and the particles streaming from
the sun.

"It's impossible to get the sense of the entire process with one
pinpoint of information," Turner said.

He called the lineup of the various crafts "lucky."

The upcoming launch of NASA's Radiation Belt Storm Probes Mission
(RBSP), scheduled for August 2012, may help to remove some
elements of chance from further studies.

"RBSP will provide two more points of view with perfect
instruments for radiation belt studies," he said.